Watch 11-Year-Old Shailene Woodley on 'The O.C.'

If the strains of Phantom Planet's "California" (here we come, right back where we started from, etc.) have been echoing through your dreams lately, it's no coincidence: Josh Schwartz's "The O.C.," which updated the classic soap opera format for teen audiences and introduced us to the indelible Seth Cohen, Ryan Atwood and Marissa Cooper, among other characters, debuted 10 years ago today.

Of course, those in the libidinous Southern Californian crew (who somehow maintained their razor-sharp hipbones even though all we ever saw them eat literally ever was bagels and vodka) weren't the only fresh faces on the scene when the show premiered. There was also bratty little sister Kaitlin Cooper, a.k.a. Shailene Woodley.

Yes, the then-11-year-old "Divergent" and "The Spectacular Now" star sulked around SoCal in spaghetti straps and equestrian gear on "The O.C." as the younger sister of Mischa Barton's Marissa Cooper. As Kaitlin, Woodley got to deliver some of the most choice lines of the show's first season ("What?! I love China! She's the prettiest pony!") and often trolled around as the sidekick to her mother, villainess Julie Cooper (Melinda Clarke). Seth Cohen (Adam Brody) once memorably described Kaitlin as "nice, and pretty smart for a 5th grader." That's all the approval we need.

Kaitlin was written off the show mid-first season (ah, the convenient far away boarding school trope), though the character returned in the third season, played for the remainder of the series by the noticeably more, ahem, mature Willa Holland. (In reality, Holland is only five months older than Woodley, but developed faster.)

"They actually re-auditioned me to bring her back," Woodley told Moviefone of the role in 2011. "But I didn't go through puberty until late: I was the 15-year-old who had no boobs. So, at 11, I was like a little mouse-child. I looked like an 8-year-old. That same year, I filmed a movie in which I was playing a 9-year-old."

In a recent interview, show creator Schwartz admitted that the revamped character came back "having aged a little bit more quickly than was probably biologically possible for Kaitlin Cooper," remembering Woodley as "really little" during her run with the show.

Though she was gone, however, she was not forgotten by Schwartz: "She drew us like a picture of her and China the horse and we still have it."

Because, as we all know, it's just not right for a little girl to love a hairless pony.